A conventional induction heating apparatus includes a plurality of heating coils and a plurality of inverters respectively connected to the heating coils, so as to inductively heat a plurality of objects to be heated (for example, refer to U.S. Patent Application Publication No. 2007/0135037 (Patent Literature 1)).
FIG. 16 is a schematic diagram showing a configuration of the conventional induction heating apparatus. The conventional induction heating apparatus shown in FIG. 16 is configured to include a commercially available AC power supply 101, a rectification circuit 102 which rectifies an alternating current from the AC power supply 101, smoothing capacitors 103, 104 which smooth a voltage from the rectification circuit 102, a first inverter 105 and a second inverter 106 which convert the respective outputs of the smoothing capacitors 103, 104 into high-frequency powers, a first heating coil 107 and a second heating coil 108 which are supplied with the high-frequency powers from the first inverter 105 and the second inverter 106 respectively, and control means (not shown) such as a microcomputer which controls the first inverter 105 and the second inverter 106 etc. In the conventional induction heating apparatus having such a configuration, the two inverters 105 and 106 share the rectification circuit 102 in use to thereby simplify the circuit configuration of the rectification circuit 102, thereby reducing the number of components.
In the conventional induction heating apparatus shown in FIG. 16, the control means such as the microcomputer controls turn-on/-off operations of semiconductor switches in the first inverter 105 and the second inverter 106, thereby supplying necessary high-frequency currents to the first heating coil 107 and the second heating coil 108 connected to the first inverter 105 and the second inverter 106 respectively.
By means of the high-frequency currents supplied to the first heating coil 107 and the second heating coil 108, a high-frequency magnetic field occurs on the first heating coil 107 and the second heating coil 108. If loads such as a pan are placed on the first heating coil 107 and the second heating coil 108 on which the high-frequency magnetic field has occurred so as to be magnetically coupled with each other, the high-frequency magnetic field is applied on those loads respectively. By means of such a high-frequency magnetic field applied on the loads, an eddy current occurs through the loads, so that the loads themselves generate heat due to this eddy current and a skin resistance of the loads themselves such as the pan.
Further, in order to adjust the amount of heating the loads such as the pan, the control means controls a drive frequency and a duty ratio (conduction ratio) of the semiconductor switches in the first inverter 105 and the second inverter 106.    Patent Literature 1: U.S. Patent Application Publication No. 2007/0135037